The genus Rhodococcus is known to produce enzymes involved in nitrile metabolism and to produce enzymes which asymmetrically reduce aminoketones. In particular, Rhodococcus erythropolis is known to have very high aminoketone asymmetric reduction activity. Such microorganisms and enzymes act on α-aminoketones to high selectively produce optically active β-aminoalcohols at high yields (for example, Patent documents 1 and 5). Thus, it has long been desired to develop a host-vector system intended for mass production of useful enzymes and the like in the genus Rhodococcus. However, the development of vectors suitable for the genus Rhodococcus as hosts has lagged behind. Only a few strains of the genus Rhodococcus have been found with plasmids, namely Rhodococcus sp. H13-A (Non-patent document 1), Rhodococcus rhodochrous ATCC4276 (Patent document 2), Rhodococcus rhodochrous ATCC4001 (Patent document 3) and Rhodococcus erythropolis IF012320 (Patent document 4).
[Patent document 1] WO01/73100
[Patent document 2] Japanese Unexamined Patent Publication HEI No. 4-148685
[Patent document 3] Japanese Unexamined Patent Publication HEI No. 4-330287
[Patent document 4] Japanese Unexamined Patent Publication HEI No. 9-28379
[Patent document 5] WO02/070714
[Non-patent document 1] J. Bacteriol., 170, 638, 1988